Contact lens solution

White, P. Scott, C. Contact lenses solutions summary. In Supplement to Contact Lens Spectrum, Viscom Publications, Inc. Norwalk, CT, Feb. 1991. 

Aerosol products are hermetically sealed, ensuring that the contents caimot leak, spill, or be contaminated. The packages can be considered to be tamper-proof. They deUver the product in an efficient manner generating Httie waste, often to sites of difficult access. By control of particle size, spray pattern, and volume deUvered per second, the product can be appHed directiy without contact by the user. For example, use of aerosol pesticides can minimize user exposure and aerosol first-aid products can soothe without applying painful pressure to a wound. Spray contact lens solutions can be appHed directiy and aerosol lubricants (qv) can be used on machinery in operation. Some preparations, such as stable foams, can only be packaged as aerosols. 

Thiomersal is employed as a preservative for eye-drops and in lower concentration, 0.001-0.004%, as a preservative for contact lens solutions. The phenylmercuric salts (0.002%) are also used for preservation of eye-drops but long-term use has led to... 

Another type of sterile ophthalmic product is the contact lens solution (section 4.5) however, unlike the other types, this is not used for medication purposes but merely as wetting, cleaning and soaking solutions for contact lenses. 

This preservative is comparatively new to ophthalmic preparations and is a polymeric quaternary ammonium germicide. Its advantage over other quaternary ammonium seems to be its inability to penetrate ocular tissues, especially the cornea. It has been used at concentrations of 0.001-0.01% in contact lens solutions as well as dry eye products. At clinically effective levels of preservative, POLYQUAD is approximately 10 times less toxic than benzalkonium chloride [87,137], Various in vitro tests and in vivo evaluations substantiate the safety of this compound [137,141,142], This preservative has been extremely useful for soft contact lens solutions because it has the least propensity to adsorb onto or absorb into these lenses, and it has a practically nonexistent potential for sensitization. Its ad-sorption/absorption with high water and high ionic lenses can be resolved by carefully balancing formulation components [143],... 

This preservative is also comparatively new to ophthalmic formulations and has been used as a disinfectant in contact lens solutions. Polyaminopropyl biguanide (polyhexamethyl biguanide) also is a polymeric compound that has a low toxicity potential at the concentrations generally used in these solutions [141, 149, 150]. 

Food and Drug Administration, Draft Testing Guidelines for Class III Soft (Hydrophilic) Contact Lens Solutions, U.S. Food and Drug Administration, Silver Springs, MD, 1985. 

The mercury containing compound, thimerosal, has found use as an antimicrobial agent and is employed in biological vaccines and contact lens solutions. The decomposition products, methy lmercury chloride, dimethy lmercury, and mercury (III) chloride, have been separated by using RPLC with a C18 column and a 3% acetonitrile mobile phase [27,31]. Long-term degradation of thimerosal was demonstrated with complete recovery for all species. 

Thimerosal is also used as a preservative in some contact lens solutions. Sensitivity to thimerosal, and concerns about chronic exposure to mercury, have encouraged the development of thimerosal-free antiseptics and contact-lens solutions. 

Toothpaste, toothbrushes, shampoo, deodorants, comb and brush, razor, shaving cream, lip balm, sunscreen, insect repellent, contact lens solutions, mirror, feminine supplies... 

Figure l6-3 Fluorescein photograph of conjunctival staining taken without barrier filter. (From Courtney RC, Lee JM. Predicting ocular intolerance of a contact lens solution by use of a filter system enhancing fluorescein staining detection. Int Contact Lens CUn 1982 9 302-310.)... 

Chemical burns of the conjimctiva usually result from inadvertent splashes of chemicals into the fece or from hydrogen peroxide contact lens solutions. Occasionally, patients may instill a chemical irritant directly into the eye, resulting in severe injury. Cigarettes, curling irons, and overexposure to UV radiation frequently cause thermal burns. 

Figure 26-56 Corneal SPK secondary to toxic/sensitivity response to contact lens solution. (Courtesy of Pat Caroline.)...

Organic mercurials mercury, silver, thiomersal, phenylmercuric acetate Broad spectrum of antibacterial activity Low capacity to organic matter, ionic and some non-ionic surfactants toxicicity Eye drops contact lens solutions... 

Methylcellulose is a vehicle used in eye-drops and contact lens solutions (SEDA-1, 369). It is non-irritant and has a good refractive index. A 1% solution is well retained in the conjunctival sac. Corneal cultures have been stimulated by methylcellulose, resulting in increased growth of cells (2) tear-film break-up time was increased four-fold with 2% methylcellulose. Hydroxypropyl methylcellulose is also used as artificial tears for people with dry eyes (3). 

Morgan JF. Comphcations associated with contact lens solutions. Ophthalmology 1979 86(6) 1107-19. 

Herbst RA, Maibach HI. Contact dermatitis caused by allergy to ophthalmic drugs and contact lens solutions. Contact Dermatitis 1991 25(5) 305-12. 

Other adverse reactions that have been reported include exfoliative dermatitis due to ointments that contain sorbic acid, and allergic conjunctivitis caused by contact lens solutions preserved with sorbic acid. ... 

Fisher AA. Allergic reactions to contact lens solutions. Cutis 1985 36 209-211. 

Thimerosal is also used in cosmetics see Section 16) and to preserve soft contact lens solutions. 

Adverse reactions to thimerosal used to preserve contact lens solutions have also been reported. Reactions include ocular redness, irritation, reduced lens tolerance, and conjunctivitis. One estimate suggests that approximately 10% of contact lens wearers may be sensitive to thimerosal. ... 

An interaction between orally administered tetracyclines and thimerosal, which resulted in varying extents of ocular irritation, has been reported in patients using a contact lens solution preserved with thimerosal. ... 

Miller JR. Sensitivity to contact lens solutions. West J Med 1984 140 791. 

Contact lens solutions coming in contact with the eye These products are classified as medical devices together with contact lenses. 

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